diff --git a/fish-rust/src/tests/encoding.rs b/fish-rust/src/tests/encoding.rs
new file mode 100644
index 000000000..34fa458d5
--- /dev/null
+++ b/fish-rust/src/tests/encoding.rs
@@ -0,0 +1,19 @@
+use crate::common::{str2wcstring, wcs2string};
+use crate::wchar::prelude::*;
+
+/// Verify correct behavior with embedded nulls.
+#[test]
+fn test_convert_nulls() {
+    let input = L!("AAA\0BBB");
+    let out_str = wcs2string(input);
+    assert_eq!(
+        input.chars().collect::<Vec<_>>(),
+        std::str::from_utf8(&out_str)
+            .unwrap()
+            .chars()
+            .collect::<Vec<_>>()
+    );
+
+    let out_wstr = str2wcstring(&out_str);
+    assert_eq!(input, &out_wstr);
+}
diff --git a/fish-rust/src/tests/mod.rs b/fish-rust/src/tests/mod.rs
index 56f6e280e..315b8d234 100644
--- a/fish-rust/src/tests/mod.rs
+++ b/fish-rust/src/tests/mod.rs
@@ -6,6 +6,7 @@ mod complete;
 mod debounce;
 #[cfg(test)]
 mod editable_line;
+mod encoding;
 mod env;
 mod env_universal_common;
 mod expand;
diff --git a/src/fish_tests.cpp b/src/fish_tests.cpp
index 2daca6bd9..44f04e934 100644
--- a/src/fish_tests.cpp
+++ b/src/fish_tests.cpp
@@ -426,34 +426,6 @@ static void perf_convert_ascii() {
     say(L"ASCII string conversion perf: %lu bytes in %llu usec", s.size(), usec);
 }
 
-// todo!("no need to port this, delete?");
-/// Verify correct behavior with embedded nulls.
-static void test_convert_nulls() {
-    say(L"Testing convert_nulls");
-    const wchar_t in[] = L"AAA\0BBB";
-    const size_t in_len = (sizeof in / sizeof *in) - 1;
-    const wcstring in_str = wcstring(in, in_len);
-    std::string out_str = wcs2string(in_str);
-    if (out_str.size() != in_len) {
-        err(L"Embedded nulls mishandled in wcs2string");
-    }
-    for (size_t i = 0; i < in_len; i++) {
-        if (in[i] != out_str.at(i)) {
-            err(L"Embedded nulls mishandled in wcs2string at index %lu", (unsigned long)i);
-        }
-    }
-
-    wcstring out_wstr = str2wcstring(out_str);
-    if (out_wstr.size() != in_len) {
-        err(L"Embedded nulls mishandled in str2wcstring");
-    }
-    for (size_t i = 0; i < in_len; i++) {
-        if (in[i] != out_wstr.at(i)) {
-            err(L"Embedded nulls mishandled in str2wcstring at index %lu", (unsigned long)i);
-        }
-    }
-}
-
 // todo!("already ported, delete this");
 static void test_iothread() {
     say(L"Testing iothreads");
@@ -1258,7 +1230,6 @@ static const test_t s_tests[]{
     {TEST_GROUP("convert"), test_convert_private_use},
     {TEST_GROUP("convert_ascii"), test_convert_ascii},
     {TEST_GROUP("perf_convert_ascii"), perf_convert_ascii, true},
-    {TEST_GROUP("convert_nulls"), test_convert_nulls},
     {TEST_GROUP("iothread"), test_iothread},
     {TEST_GROUP("pthread"), test_pthread},
     {TEST_GROUP("lru"), test_lru},